Correct processing of non-string members of a base URL record

Some of these values may be null (or in the case of port, an integer)
and must be converted to strings before they can be applied to
URLPatternInit.

Fixes #202.

spec.bs

@@ -18,6 +18,9 @@ spec: ECMASCRIPT; urlPrefix: https://tc39.es/ecma262/
   type: dfn
     text: IdentifierPart; url: #prod-IdentifierPart
     text: IdentifierStart; url: #prod-IdentifierStart
+spec: URL; urlPrefix: https://url.spec.whatwg.org/
+  type: dfn
+    text: serialize an integer; url: #serialize-an-integer
 </pre>
 
 <h2 id=urlpattern-class>The {{URLPattern}} class</h2>
@@ -1823,11 +1826,22 @@ To <dfn>convert a modifier to a string</dfn> given a [=part/modifier=] |modifier
     1. If |init|["{{URLPatternInit/protocol}}"] does not [=map/exist=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/scheme=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}" and "{{URLPatternInit/username}}", then set |result|["{{URLPatternInit/username}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/username=] and |type|.
     1. If |type| is not "`pattern`" and |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/username}}" and "{{URLPatternInit/password}}", then set |result|["{{URLPatternInit/password}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/password=] and |type|.
-    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/host=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then set |result|["{{URLPatternInit/port}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/port=] and |type|.
+    1. If |init| [=map/contains=] neither "{{URLPatternInit/protocol}}" nor "{{URLPatternInit/hostname}}", then:
+      1. Let |baseHost| be |baseURL|'s [=url/host=].
+      1. If |baseHost| is null, then set |baseHost| to the empty string.
+      1. Set |result|["{{URLPatternInit/hostname}}"] to the result of [=processing a base URL string=] given |baseHost| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", and "{{URLPatternInit/port}}", then:
+      1. If |baseURL|'s [=url/port=] is null, then set |result|["{{URLPatternInit/port}}"] to the empty string.
+      1. Otherwise, set |result|["{{URLPatternInit/port}}"] to |baseURL|'s [=url/port=], [=serialize an integer|serialized=].
     1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", and "{{URLPatternInit/pathname}}", then set |result|["{{URLPatternInit/pathname}}"] to the result of [=processing a base URL string=] given the result of [=URL path serializing=] |baseURL| and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/query=] and |type|.
-    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseURL|'s [=url/fragment=] and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", and "{{URLPatternInit/search}}", then:
+      1. Let |baseQuery| be |baseURL|'s [=url/query=].
+      1. If |baseQuery| is null, then set |baseQuery| to the empty string.
+      1. Set |result|["{{URLPatternInit/search}}"] to the result of [=processing a base URL string=] given |baseQuery| and |type|.
+    1. If |init| [=map/contains=] none of "{{URLPatternInit/protocol}}", "{{URLPatternInit/hostname}}", "{{URLPatternInit/port}}", "{{URLPatternInit/pathname}}", "{{URLPatternInit/search}}", and "{{URLPatternInit/hash}}", then:
+      1. Let |baseFragment| be |baseURL|'s [=url/fragment=].
+      1. If |baseFragment| is null, then set |baseFragment| to the empty string.
+      1. Set |result|["{{URLPatternInit/hash}}"] to the result of [=processing a base URL string=] given |baseFragment| and |type|.
   1. If |init|["{{URLPatternInit/protocol}}"] [=map/exists=], then set |result|["{{URLPatternInit/protocol}}"] to the result of [=process protocol for init=] given |init|["{{URLPatternInit/protocol}}"] and |type|.
   1. If |init|["{{URLPatternInit/username}}"] [=map/exists=], then set |result|["{{URLPatternInit/username}}"] to the result of [=process username for init=] given |init|["{{URLPatternInit/username}}"] and |type|.
   1. If |init|["{{URLPatternInit/password}}"] [=map/exists=], then set |result|["{{URLPatternInit/password}}"] to the result of [=process password for init=] given |init|["{{URLPatternInit/password}}"] and |type|.